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simplified scoped_bilock impl

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This commit is contained in:
joaquintides
2023-03-30 12:13:58 +02:00
parent 6399dfd1e4
commit f02afbc815
1 changed files with 18 additions and 17 deletions
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35
include/boost/unordered/detail/foa/concurrent_table.hpp
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@ -54,6 +54,10 @@ struct alignas(64) cacheline_protected:T
using T::T;
};
#if defined(BOOST_MSVC)
#pragma warning(pop) /* C4324 */
#endif
template<typename Mutex,std::size_t N>
class multimutex
{
@ -105,40 +109,37 @@ private:
Mutex &m;
};
/* copied from boost/multi_index/detail/scoped_bilock.hpp */
/* inspired by boost/multi_index/detail/scoped_bilock.hpp */
template<typename Mutex>
class scoped_bilock
{
public:
scoped_bilock(Mutex& m1,Mutex& m2)noexcept:mutex_eq{&m1==&m2}
scoped_bilock(Mutex& m1,Mutex& m2)noexcept
{
bool mutex_lt=std::less<Mutex*>{}(&m1,&m2);
::new (static_cast<void*>(&storage1)) lock_guard_type(mutex_lt?m1:m2);
if(!mutex_eq)
::new (static_cast<void*>(&storage2)) lock_guard_type(mutex_lt?m2:m1);
pm1=mutex_lt?&m1:&m2;
pm1->lock();
if(&m1==&m2){
pm2=nullptr;
}
else{
pm2=mutex_lt?&m2:&m1;
pm2->lock();
}
}
~scoped_bilock()noexcept
{
reinterpret_cast<lock_guard_type*>(&storage1)->~lock_guard_type();
if(!mutex_eq)
reinterpret_cast<lock_guard_type*>(&storage2)->~lock_guard_type();
if(pm2)pm2->unlock();
pm1->unlock();
}
private:
using lock_guard_type=lock_guard<Mutex>;
bool mutex_eq;
alignas(lock_guard_type) unsigned char storage1[sizeof(lock_guard_type)],
storage2[sizeof(lock_guard_type)];
Mutex *pm1,*pm2;
};
#if defined(BOOST_MSVC)
#pragma warning(pop) /* C4324 */
#endif
/* TODO: describe atomic_integral and group_access */
template<typename Integral>